<template>
    <el-select :clearable="clearable" :value="valueTitle" @clear="clearHandle" ref="select" :style="'width:'+width">
        <el-option :label="valueTitle" :value="valueTitle">
            <el-tree :accordion="accordion" :data="options" empty-text="--请选择--" :default-expanded-keys="defaultExpandedKey" :node-key="props.value" :props="props" @node-click="handleNodeClick" id="tree-option" ref="selectTree"></el-tree>
        </el-option>
    </el-select>
</template>
<script>
export default {
    name: 'el-tree-select',
    props: {
        /* 配置项 */
        props: {
            type: Object,
            default: () => {
                return {
                    value: 'id', // ID字段名
                    label: 'title', // 显示名称
                    children: 'children', // 子级字段名
                }
            },
        },
        /* 选项列表数据(树形结构的对象数组) */
        options: {
            type: Array,
            default: () => {
                return []
            },
        },
        /* 初始值 */
        value: {
            type: Number,
            default: () => {
                return null
            },
        },
        /* 可清空选项 */
        clearable: {
            type: Boolean,
            default: () => {
                return true
            },
        },
        /* 自动收起 */
        accordion: {
            type: Boolean,
            default: () => {
                return false
            },
        },
        width:{
            type: String,
            default: () => {
                return "191px"
            },
        }
    },
    data() {
        return {
            valueId: this.value, // 初始值
            valueTitle: '',
            defaultExpandedKey: [],
        }
    },
    mounted() {
        this.initHandle()
    },
    model: {
      // 需要双向绑定的 props 变量名称，也就是父组件通过 v-model 与子组件双向绑定的变量
      prop: 'value',
      // 定义由 $emit 传递变量的名称
      event: 'getValue'
    },
    methods: {
        // 初始化值
        initHandle() {
            if (this.valueId) {
                this.valueTitle = this.$refs.selectTree.getNode(this.valueId).data[this.props.label] // 初始化显示
                this.$refs.selectTree.setCurrentKey(this.valueId) // 设置默认选中
                this.defaultExpandedKey = [this.valueId] // 设置默认展开
            }
            this.$nextTick(() => {
                let scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
                let scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
                scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
                scrollBar.forEach((ele) => (ele.style.width = 0))
            })
        },
        // 切换选项
        handleNodeClick(node) {
            this.valueTitle = node[this.props.label]
            this.valueId = node[this.props.value]
            
            this.$emit('getValue', this.valueId)
            this.defaultExpandedKey = []
			this.$refs.select.blur()
        },
        // 清除选中
        clearHandle() {
            this.valueTitle = ''
            this.valueId = null
            this.defaultExpandedKey = []
            this.clearSelected()
            this.$emit('getValue', null)
        },
        /* 清空选中样式 */
        clearSelected() {
            let allNode = document.querySelectorAll('#tree-option .el-tree-node')
            allNode.forEach((element) => element.classList.remove('is-current'))
        },
    },
    watch: {
        value() {
            this.valueId = this.value
            this.initHandle()
        },
    },
}
</script>

<style lang="scss" scoped>
.el-scrollbar .el-scrollbar__view .el-select-dropdown__item {
    height: auto;
    max-height: 274px;
    padding: 0;
    overflow: hidden;
    overflow-y: auto;
}
.el-select-dropdown__item.selected {
    font-weight: normal;
}
ul li >>> .el-tree .el-tree-node__content {
    height: auto;
    padding: 0 20px;
}
.el-tree-node__label {
    font-weight: normal;
}
.el-tree >>> .is-current .el-tree-node__label {
    color: #409eff;
    font-weight: 700;
}
.el-tree >>> .is-current .el-tree-node__children .el-tree-node__label {
    color: #606266;
    font-weight: normal;
}
</style>